Significant association of TH01 allele 9.3 and SIDS

The Autosomal Short Tandem Repeat Polymorphisms Are Potentially Associated with Cardiovascular Disease Predisposition in the Latin American Population: A Mini Review

According to the World Health Organization, cardiovascular diseases (CVDs) are the leading cause of death worldwide across nearly all ethnic groups. Inherited cardiac conditions comprise a wide spectrum of diseases that affect the heart, including abnormal structural features and functional impairments. In Latin America, CVDs are the leading cause of death within the region. Factors such as population aging, unhealthy diet, obesity, smoking, and a sedentary lifestyle have increased the risk of CVD. The Latin American population is characterized by its diverse ethnic composition with varying percentages of each ancestral component (African, European, and Native American ancestry). Short tandem repeats (STRs) are DNA sequences with 2-6 base pair repetitions and constitute ~3% of the human genome. Importantly, significant allele frequency variations exist between different populations. While studies have described that STRs are in noncoding regions of the DNA, increasing evidence suggests that simple sequence repeat variations may be critical for proper gene activity and regulation. Furthermore, several STRs have been identified as potential disease predisposition markers. The present review is aimed at comparing and describing the frequencies of autosomal STR polymorphisms potentially associated with cardiovascular disease predisposition in Latin America compared with other populations.

The Impact of Leukemia on the Detection of Short Tandem Repeat (STR) Markers

INTRODUCTION

Short tandem repeats (STRs) have been used for various identity typing methods worldwide. They have high discrimination power in human identification in forensics, paternity testing, missed personal identification, genetic diseases, and gene regulatory functions. They have also been used to detect and monitor the stability of diseases, including various types of cancer. This study aimed to investigate the impact of leukemia on the detection and stability of STR markers.

METHODS

DNA was isolated from 30 participants (15 with chronic myeloid leukemia( CML) and 15 healthy controls) and used to amplify STR markers using specific primers.

RESULTS

We found that the blood of those with leukemia had more 9.3 and 9 alleles at the tyrosine hydroxylase 1 (TH01) marker than the blood of the healthy control samples. The results of this study will help researchers understand leukemia's effect on the detection and stability of STR markers in leukemic patients compared to healthy individuals.

CONCLUSION

Our results demonstrate that STR markers could become useful in genetic studies of leukemia cases.

Thermal Effects on DNA Degradation in Blood and Seminal Stains: Forensic View

Forensic investigations using DNA analysis have been grown rapidly. Samples retrieved from crime scene may be exposed to different conditions before proceeding. This study aimed to evaluate the effect of different grades of temperature and burn on DNA extraction and typing.

METHODS

Seven mL of blood and four mL of semen were collected from each volunteer. Effects of temperature grades (100 °C, 50 °C, 37 °C, 4 °C, -20 °C, and burn) on blood and seminal stain were tested.

RESULTS

Bloodstains exposed to temperature grades 100 °C, 50 °C, 37 °C, 4 °C, and -20 °C can be identified using preliminary test while burnt blood stain cannot. Seminal stains exposed to temperature grades 37 °C, 4 °C, and -20 °C can be identified by Florence test while those exposed to 100 °C, 50 °C, and burn cannot. Blood and seminal stains exposed to temperature grades 100 °C, 50 °C, and burn show marked reduction in DNA concentration while maximum DNA conc could be recovered from stains exposed to temperature grade temperature. Both blood and seminal DNA was affected only in case of burn without significant difference between THO1 and Amelogenin primers.

CONCLUSION

High environmental temperature affect the quantity of extracted DNA from different stains but less effect on the quality of extracted DNA. Burn affects both preliminary test, DNA quantity, and quality in stains.

Forensic Autosomal Short Tandem Repeats and Their Potential Association With Phenotype

Forensic DNA profiling utilizes autosomal short tandem repeat (STR) markers to establish identity of missing persons, confirm familial relations, and link persons of interest to crime scenes. It is a widely accepted notion that genetic markers used in forensic applications are not predictive of phenotype. At present, there has been no demonstration of forensic STR variants directly causing or predicting disease. Such a demonstration would have many legal and ethical implications. For example, is there a duty to inform a DNA donor if a medical condition is discovered during routine analysis of their sample? In this review, we evaluate the possibility that forensic STRs could provide information beyond mere identity. An extensive search of the literature returned 107 articles associating a forensic STR with a trait. A total of 57 of these studies met our inclusion criteria: a reported link between a STR-inclusive gene and a phenotype and a statistical analysis reporting a p-value less than 0.05. A total of 50 unique traits were associated with the 24 markers included in the 57 studies. TH01 had the greatest number of associations with 27 traits reportedly linked to 40 different genotypes. Five of the articles associated TH01 with schizophrenia. None of the associations found were independently causative or predictive of disease. Regardless, the likelihood of identifying significant associations is increasing as the function of non-coding STRs in gene expression is steadily revealed. It is recommended that regular reviews take place in order to remain aware of future studies that identify a functional role for any forensic STRs.

Assigning cause for sudden unexpected infant death

We have reached a conundrum in assigning cause of death for sudden unexpected infant deaths. We summarize the discordant perspectives and approaches and how they have occurred, and recommend a pathway toward improved consistency. This lack of consistency affects pediatricians and other health care professionals, scientific investigators, medical examiners and coroners, law enforcement agencies, families, and support or advocacy groups. We recommend that an interdisciplinary international committee be organized to review current approaches for assigning cause of death, and to identify a consensus strategy for improving consistency. This effort will need to encompass intrinsic risk factors or infant vulnerability in addition to known environmental risk factors including unsafe sleep settings, and must be sufficiently flexible to accommodate a progressively expanding knowledge base.

Tyrosine hydroxylase TH01 9.3 allele in the occurrence of sudden infant death syndrome in Swiss Caucasians

Catecholamines, especially noradrenalin, are essential in the control of respiration and arousal. Thus, an impaired production of these neurotransmitters may contribute to the occurrence of sudden infant death syndrome (SIDS). The first step of the noradrenergic synthesis pathway is catalyzed by the enzyme tyrosine hydroxylase (TH). The TH-encoding gene contains a tetrameric short tandem repeat in intron 1 (TH01), with allele 9.3 reported to be associated with SIDS in German infants. We investigated the allelic frequency of the TH01 marker in 171 Swiss SIDS infants and 500 healthy and gender-matched Caucasian adults. In our study population, the allelic frequency of the 9.3 allele is similarly distributed in SIDS cases and controls (27.2% vs. 25.6%; p-value = 0.562). Nevertheless, the TH-encoding gene is only one of several genes involved in the noradrenergic biosynthesis pathway. Therefore, further genetic investigations are required with focus on the whole noradrenergic signaling system.

Sodium/proton exchanger 3 (NHE3) and sudden infant death syndrome (SIDS)

The sodium/proton exchanger protein 3 (NHE3) is located in chemosensitive areas of the medulla oblongata and plays an important role in the central control of respiration. Overexpression of NHE3 is correlated with lower respiration and might therefore contribute to the vulnerability of infants dying suddenly and unexpected (sudden infant death syndrome, SIDS). Our aim in this study was to verify already reported genetic variations in the NHE3 gene in an independent SIDS cohort from Switzerland. Two single nucleotide polymorphisms (SNPs) in the promoter region (G1131A and C1197T) and one variation in the coding sequence of exon 16 (C2405T) in the NHE3 gene were analyzed in 160 Caucasian SIDS infants and 192 Swiss adult controls by using a single base extension method (SNaPshot multiplex). No significant differences were detected in the allelic frequencies of the three NHE3 polymorphisms between SIDS cases and controls. We conclude that the three investigated NHE3 SNPs are unlikely to play a major role in the pathogenesis of SIDS in Caucasian infants. However, further genetic investigations in different ethnicities are required to determine whether variations in NHE3 are associated with an increased SIDS risk.

A model-based 'varimax' sampling strategy for a heterogeneous population

BACKGROUND AND AIMS

Sampling strategies are planned to enhance the homogeneity of a sample, hence to minimize confounding errors. A sampling strategy was developed to minimize the variation within population groups. Karachi, the largest urban agglomeration in Pakistan, was used as a model population.

SUBJECTS AND METHODS

Blood groups ABO and Rh factor were determined for 3000 unrelated individuals selected through simple random sampling. Among them five population groups, namely Balochi, Muhajir, Pathan, Punjabi and Sindhi, based on paternal ethnicity were identified. An index was designed to measure the proportion of admixture at parental and grandparental levels. Population models based on index score were proposed. For validation, 175 individuals selected through stratified random sampling were genotyped for the three STR loci CSF1PO, TPOX and TH01.

RESULTS

ANOVA showed significant differences across the population groups for blood groups and STR loci distribution. Gene diversity was higher across the sub-population model than in the agglomerated population. At parental level gene diversities are significantly higher across No admixture models than Admixture models. At grandparental level the difference was not significant.

CONCLUSION

A sub-population model with no admixture at parental level was justified for sampling the heterogeneous population of Karachi.

The dorsal motor nucleus of the vagus (DMNV) in sudden infant death syndrome (SIDS): pathways leading to apoptosis

Sudden infant death syndrome (SIDS) remains the commonest cause of death in the post-neonatal period in the developed world. A leading hypothesis is that an abnormality in the brainstem of infants who succumb to SIDS, either causes or predisposes to failure to respond appropriately to an exogenous stressor. Neuronal apoptosis can lead to loss of cardiorespiratory reflexes, compromise of the infant's ability to respond to stressors such as hypoxia, and ultimately a sleep-related death. The dorsal motor nucleus of the vagus (DMNV) is a medullary autonomic nucleus where abnormalities have regularly been identified in SIDS research. This review collates neurochemical findings documented over the last 30 years, including data from our laboratory focusing on neuronal apoptosis and the DMNV, and provides potential therapeutic interventions targeting neurotransmitters, growth factors and/or genes.

Association between a functional polymorphism in the MAOA gene and sudden infant death syndrome

OBJECTIVES

Abnormalities in the serotonergic as well as the noradrenergic neuronal systems are believed to contribute to sudden infant death syndrome (SIDS). The X-chromosomal monoamine oxidase A (MAOA) gene is of importance for both systems and up to now no systematic study on a functional polymorphism in this gene has been performed in a sufficiently large group.

METHODS

We investigated a functional MAOA promoter length polymorphism in 156 white SIDS cases and 260 gender- and age-matched control subjects by using capillary electrophoresis and fluorescence dye labeled primers.

RESULTS

The pooled low-expressing alleles *2 and *3 were more frequent in the 99 male SIDS cases than in 161 male control subjects (44.4% vs 25.5%). However, there were no differences in female cases. The frequency of low expression alleles varied significantly with the age at death and were significantly more frequent in children who died between an age of 46 and 154 days than at an older age (54.9% vs 22.6%).

CONCLUSIONS

Our results indicate a relationship between SIDS and the MAOA genotype in boys via influencing serotonergic and noradrenergic neurons in the brainstem. This locus is the first X-chromosomal locus associated with SIDS. Our results support the theory that abnormalities in the brainstem contribute to a subset of SIDS, at least in boys. Moreover, we argue that not only the serotonergic system but also other neuronal systems, among those the noradrenergic one, are involved.